using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.Logging;
using JGSY.CMS.LowCode.Platform.Application.Interfaces;
using JGSY.CMS.LowCode.Platform.Application.DTOs;
using JGSY.CMS.LowCode.Platform.Infrastructure.Configuration;
using System.Text;
using System.Security.Cryptography;

namespace JGSY.CMS.LowCode.Platform.Infrastructure.Services
{
    /// <summary>
    /// 腾讯云COS存储服务实现
    /// </summary>
    public class TencentCosStorageService : ICloudStorageService
    {
        private readonly ILogger<TencentCosStorageService> _logger;
        private readonly TencentCosConfiguration _config;

        public TencentCosStorageService(
            EnhancedConfigurationMappingFactory configFactory, 
            ILogger<TencentCosStorageService> logger)
        {
            _logger = logger;
            var cloudStorageConfig = configFactory.GetCloudStorageConfiguration();
            _config = cloudStorageConfig.TencentCos;

            if (!_config.Enabled)
            {
                _logger.LogWarning("腾讯云COS存储服务未启用");
            }
        }

    public Task<string> UploadAsync(Stream file, string fileName, string? folder = null, string? contentType = null)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                var objectKey = BuildObjectKey(folder, fileName);
                
                // 这里需要集成腾讯云COS SDK
                // 目前提供模拟实现，实际使用时需要添加 COSXML.dll 引用
                
                _logger.LogInformation("模拟上传文件到腾讯云COS: {FileName} -> {ObjectKey}", fileName, objectKey);
                
                // 模拟文件URL
                var fileUrl = $"https://{_config.BucketName}-{_config.AppId}.cos.{_config.Region}.myqcloud.com/{objectKey}";
                
                _logger.LogInformation("文件上传到腾讯云COS成功: {FileName} -> {FileUrl}", fileName, fileUrl);
                
                return Task.FromResult(fileUrl);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "文件上传到腾讯云COS失败: {FileName}", fileName);
                throw;
            }
        }

        public async Task<string> UploadAsync(IFormFile file, string? folder = null)
        {
            if (file == null || file.Length == 0)
            {
                throw new ArgumentException("文件不能为空", nameof(file));
            }

            using var stream = file.OpenReadStream();
            return await UploadAsync(stream, file.FileName, folder, file.ContentType);
        }

        public async Task<List<string>> UploadBatchAsync(IEnumerable<IFormFile> files, string? folder = null)
        {
            var results = new List<string>();
            
            foreach (var file in files)
            {
                if (file?.Length > 0)
                {
                    try
                    {
                        var url = await UploadAsync(file, folder);
                        results.Add(url);
                    }
                    catch (Exception ex)
                    {
                        _logger.LogError(ex, "批量上传中文件失败: {FileName}", file.FileName);
                        // 继续处理其他文件
                    }
                }
            }

            return results;
        }

        public Task<Stream> DownloadAsync(string fileUrl)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            // 模拟实现
            _logger.LogInformation("模拟从腾讯云COS下载文件: {FileUrl}", fileUrl);
            return Task.FromResult(Stream.Null);
        }

        public Task<bool> DeleteAsync(string fileUrl)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                var objectKey = ExtractObjectKeyFromUrl(fileUrl);
                
                // 模拟删除
                _logger.LogInformation("模拟删除腾讯云COS文件: {ObjectKey}", objectKey);
                
                return Task.FromResult(true);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "删除腾讯云COS文件失败: {FileUrl}", fileUrl);
                return Task.FromResult(false);
            }
        }

    public async Task<int> DeleteBatchAsync(IEnumerable<string> fileUrls)
        {
            var successCount = 0;
            
            foreach (var fileUrl in fileUrls)
            {
                try
                {
                    var deleted = await DeleteAsync(fileUrl);
                    if (deleted) successCount++;
                }
                catch (Exception ex)
                {
                    _logger.LogError(ex, "批量删除中文件失败: {FileUrl}", fileUrl);
                }
            }

            return successCount;
        }

        public Task<bool> ExistsAsync(string fileUrl)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            // 模拟实现
            return Task.FromResult(true);
        }

        public Task<CloudFileInfo?> GetFileInfoAsync(string fileUrl)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                var objectKey = ExtractObjectKeyFromUrl(fileUrl);
                
                // 模拟文件信息
                var fileInfo = new CloudFileInfo
                {
                    FileName = Path.GetFileName(objectKey),
                    Size = 0, // 需要从实际API获取
                    ContentType = GetContentType(Path.GetExtension(objectKey)),
                    LastModified = DateTime.UtcNow,
                    ETag = Guid.NewGuid().ToString("N"),
                    Url = fileUrl
                };

                return Task.FromResult<CloudFileInfo?>(fileInfo);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "获取腾讯云COS文件信息失败: {FileUrl}", fileUrl);
                return Task.FromResult<CloudFileInfo?>(null);
            }
        }

        public Task<PreSignedUploadInfo> GeneratePreSignedUploadUrlAsync(string fileName, string? folder = null, TimeSpan? expiration = null)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                var objectKey = BuildObjectKey(folder, fileName);
                var expiry = DateTime.UtcNow.Add(expiration ?? TimeSpan.FromHours(1));
                
                // 模拟预签名URL生成
                var preSignedUrl = GeneratePreSignedUrl(objectKey, expiry);
                var fileUrl = $"https://{_config.BucketName}-{_config.AppId}.cos.{_config.Region}.myqcloud.com/{objectKey}";

                var info = new PreSignedUploadInfo
                {
                    UploadUrl = preSignedUrl,
                    FileUrl = fileUrl,
                    ExpiresAt = expiry,
                    FormFields = new Dictionary<string, string>
                    {
                        { "Content-Type", GetContentType(Path.GetExtension(fileName)) }
                    }
                };

                return Task.FromResult(info);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "生成腾讯云COS预签名上传URL失败: {FileName}", fileName);
                throw;
            }
        }

        public Task<string> GeneratePreSignedDownloadUrlAsync(string fileUrl, TimeSpan? expiration = null)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                var expiry = DateTime.UtcNow.Add(expiration ?? TimeSpan.FromHours(1));
                var objectKey = ExtractObjectKeyFromUrl(fileUrl);
                var downloadUrl = GeneratePreSignedUrl(objectKey, expiry);
                
                return Task.FromResult(downloadUrl);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "生成腾讯云COS预签名下载URL失败: {FileUrl}", fileUrl);
                throw;
            }
        }

        public Task<List<CloudFileInfo>> ListFilesAsync(string? folder = null, int maxResults = 100)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            // 模拟文件列表
            var files = new List<CloudFileInfo>();
            
            for (int i = 0; i < Math.Min(maxResults, 5); i++)
            {
                files.Add(new CloudFileInfo
                {
                    FileName = $"sample-file-{i}.txt",
                    FilePath = string.IsNullOrEmpty(folder) ? $"sample-file-{i}.txt" : $"{folder}/sample-file-{i}.txt",
                    Url = $"https://{_config.BucketName}-{_config.AppId}.cos.{_config.Region}.myqcloud.com/{folder}/sample-file-{i}.txt",
                    Size = 1024 * (i + 1),
                    ContentType = "text/plain",
                    LastModified = DateTime.UtcNow.AddDays(-i),
                    ETag = Guid.NewGuid().ToString("N")
                });
            }
            
            return Task.FromResult(files);
        }

    public Task<string> CopyAsync(string sourceUrl, string destinationPath)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                var sourceKey = ExtractObjectKeyFromUrl(sourceUrl);
                var destKey = destinationPath.TrimStart('/');
                
                // 模拟复制操作
                _logger.LogInformation("模拟复制腾讯云COS文件: {SourceKey} -> {DestKey}", sourceKey, destKey);
                
                var newUrl = $"https://{_config.BucketName}-{_config.AppId}.cos.{_config.Region}.myqcloud.com/{destKey}";
        return Task.FromResult(newUrl);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "腾讯云COS文件复制失败: {SourceUrl} -> {DestinationPath}", sourceUrl, destinationPath);
                throw;
            }
        }

    public async Task<string> MoveAsync(string sourceUrl, string destinationPath)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            try
            {
                // 先复制后删除
        var newUrl = await CopyAsync(sourceUrl, destinationPath);
                await DeleteAsync(sourceUrl);
                
                return newUrl;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "腾讯云COS文件移动失败: {SourceUrl} -> {DestinationPath}", sourceUrl, destinationPath);
                throw;
            }
        }

        public Task<StorageStatistics> GetStatisticsAsync(string? folder = null)
        {
            if (!_config.Enabled)
                throw new InvalidOperationException("腾讯云COS存储服务未启用");

            // 模拟统计信息
            var stats = new StorageStatistics
            {
                TotalFiles = 100,
                TotalSize = 1024 * 1024 * 500 // 500MB
            };
            
            return Task.FromResult(stats);
        }

        private string BuildObjectKey(string? folder, string fileName)
        {
            var sanitizedFileName = SanitizeFileName(fileName);
            
            if (string.IsNullOrEmpty(folder))
            {
                return $"{DateTime.UtcNow:yyyy/MM/dd}/{sanitizedFileName}";
            }
            
            return $"{folder.Trim('/')}/{sanitizedFileName}";
        }

        private string ExtractObjectKeyFromUrl(string fileUrl)
        {
            var uri = new Uri(fileUrl);
            return uri.AbsolutePath.TrimStart('/');
        }

        private string SanitizeFileName(string fileName)
        {
            var invalidChars = Path.GetInvalidFileNameChars();
            var sanitized = string.Join("_", fileName.Split(invalidChars, StringSplitOptions.RemoveEmptyEntries));
            return string.IsNullOrEmpty(sanitized) ? Guid.NewGuid().ToString("N") : sanitized;
        }

        private string GetContentType(string extension)
        {
            return extension.ToLowerInvariant() switch
            {
                ".jpg" or ".jpeg" => "image/jpeg",
                ".png" => "image/png",
                ".gif" => "image/gif",
                ".pdf" => "application/pdf",
                ".txt" => "text/plain",
                ".doc" => "application/msword",
                ".docx" => "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
                ".mp4" => "video/mp4",
                ".mp3" => "audio/mpeg",
                ".zip" => "application/zip",
                _ => "application/octet-stream"
            };
        }

        private string GeneratePreSignedUrl(string objectKey, DateTime expiry)
        {
            // 模拟预签名URL生成（实际需要按腾讯云COS规范生成）
            var timestamp = ((DateTimeOffset)expiry).ToUnixTimeSeconds();
            var signature = GenerateSignature(objectKey, timestamp);
            
            return $"https://{_config.BucketName}-{_config.AppId}.cos.{_config.Region}.myqcloud.com/{objectKey}" +
                   $"?q-sign-algorithm=sha1&q-ak={_config.SecretId}&q-sign-time={timestamp}&q-signature={signature}";
        }

        private string GenerateSignature(string objectKey, long timestamp)
        {
            // 简化的签名生成（实际需要按腾讯云COS规范）
            using var hmac = new HMACSHA1(Encoding.UTF8.GetBytes(_config.SecretKey));
            var data = Encoding.UTF8.GetBytes($"{objectKey}:{timestamp}");
            var hash = hmac.ComputeHash(data);
            return Convert.ToHexString(hash).ToLowerInvariant();
        }
    }
}
